The present invention relates generally to the field of fiberboard substrates. More particularly, the present invention relates to an acoustical panel having a substantially monolithic appearance with an acceptable noise reduction coefficient.
Fibrous acoustical panels are typically constructed using strong but relatively inexpensive materials such as newsprint paper, perlite, clays, mineral wool, and binder, such as starch. In order to achieve the requisite acoustical performance, the panel must be porous, especially on the surface of the panel. Examples of porous acoustical panels are described in U.S. Pat. Nos. 1,769,519; 4,911,788; and 5,071,511.
It is widely known in the industry that there is a balance between acoustical performance and visual aesthetics. A highly porous, low-density material may exhibit exceptional acoustical performance. However, such highly porous, low-density material tends to be fragile and difficult to handle and tends to exhibit poor durability, scrubability, tensile strength and, as a result, may not be visually appealing. The production processes and slurry recipes for acoustical panels are often manipulated in an attempt to balance these inherent tradeoffs.
For example, once the acoustical panel is formed, the panel can be further processed, e.g. embossed or punched with small holes, to further enhance the acoustical absorption capabilities of the panel while at the same time maintaining aesthetic appeal. An alternative technique for providing acoustical capabilities and aesthetic appeal is to laminate additional layers of material to the base panel. Generally, the acoustical performance of the laminated panel is largely a function of the soft, acoustically absorbent inner layer, while the outer layer which faces the room enhances the panel's durability, scrubability, and aesthetics. While laminated panels provide a good balance between performance, durability and visual aesthetics, such panels are relatively expensive to manufacture as the outer layer material usually is a high-cost constituent and lamination requires additional machinery, materials, and human resources.
U.S. Pat. No. 6,103,360 describes yet another attempt to provide a panel having high acoustical capabilities. Here, a coating composition which includes water, a binder and filler is placed on the acoustical panel. The filler contains particles having three different sizes. Due to the presence of the different sized particles, the coating composition is both durable and provides for high light reflectance. The coating is discontinuous, i.e. porous, enabling sound to pass through to an acoustical substrate. Similarly, U.S. Patent Application Publication No. 2004/0062898 describes a coating composition having filler particles, a binder and a liquid carrier. The filler particles are of a sufficient size to impart a textured appearance to the substrate. The coating composition preserves the acoustic performance characteristics of the substrate to which it is applied, while imparting a textured appearance to the substrate, making the substrate virtually indistinguishable from the surrounding panels.
However, the need remains for an inexpensively produced, fibrous substrate which has a monolithic appearance, a high light reflectance value and high sound absorption capabilities.